When you say the Tesla gateway holds the main breaker for the house, do you mean it's the service entrance disconnect, and that there are no breakers in the panel that has the meter on it?
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PowerWall 2 Interface with a Generator
- Thread starter shs1
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When you say the Tesla gateway holds the main breaker for the house, do you mean it's the service entrance disconnect, and that there are no breakers in the panel that has the meter on it?
I would like to propose a solution to the generator problem. Install the generator transfer switch between the Powerwall Backup Gateway and the utility grid. Install a relay/contactor that can disconnect the solar panel inverters. Then setup small computer that can talk to the Powerwall. I believe that there is an owners API. All you need from the Powerwall is the current state of charge (SoC). When the SoC drops to say 10%, the computer disconnects the solar panels and fires up the generator and throws the generator transfer switch. We let the generator run until the SoC gets up to say 50% or until the grid comes back. Then we shut off the generator and reconnect the solar and the grid. This setup should allow the Powerwall and the generator to cycle until either the solar or the grid come back on line. It is fully automatic. The only down side is throwing away a little solar while the generator is running. The only questions I have are: Is the generator power clean enough for the Powerwall? And how do we safely disconnect the panel inverters without generating damaging transients.
@PaulSawyer, do you happen to have the URI's to interrogate the status and/or control the state of the (solar) transfer switch(s) within the EG?
We "know" some EG URI's to get certain information (eg: meter statistics) of which some of these include battery SoC, Grid and Solar generation and Home/Load and so-forth. With the information already available it is not difficult to monitor/notify about changed conditions. One can also emulate a genset start/stop with this information.
In designing the PW-2 and the EG it would have seemed logical to have allowed for several input sources:
1. Grid
2. Solar
3. Genset
4. Alternate (perhaps wind, micro-hydro or both)
Under software monitoring and control, it would then be viable to determine that:
A. If the grid has failed and solar is available continue (which is what the PW-2 does at this time) [combining battery and solar]
B. If the grid has failed possibly start genset - depending on load and/or battery SoC or other user parameters
C. Do not allow power flow from genset to solar (does not happen from grid to solar)
D. Do not allow power flow from solar to genset (does happen from solar to grid)
E. If grid has failed, isolate unit from grid but continue with battery and/or solar to load (does this now) [while continuing to monitor grid]
Under the right conditions for the above, generate a genset start/stop signal and connect/disconnect the appropriate sources and of course notify someone [snmp, e-mail, SMS or a combination]
I have 4 CT's on my PW-2; 1 is grid, 4 is solar and was told that 2 and 3 are for use with the other 2 phases of a 3 phase installation. I do not have schematic diagrams of the internals of the EG or the PW-2 but had hoped these unused inputs were like the description above.
Cheers,
Harry E.
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We "know" some EG URI's to get certain information (eg: meter statistics) of which some of these include battery SoC, Grid and Solar generation and Home/Load and so-forth. With the information already available it is not difficult to monitor/notify about changed conditions. One can also emulate a genset start/stop with this information.
In designing the PW-2 and the EG it would have seemed logical to have allowed for several input sources:
1. Grid
2. Solar
3. Genset
4. Alternate (perhaps wind, micro-hydro or both)
Under software monitoring and control, it would then be viable to determine that:
A. If the grid has failed and solar is available continue (which is what the PW-2 does at this time) [combining battery and solar]
B. If the grid has failed possibly start genset - depending on load and/or battery SoC or other user parameters
C. Do not allow power flow from genset to solar (does not happen from grid to solar)
D. Do not allow power flow from solar to genset (does happen from solar to grid)
E. If grid has failed, isolate unit from grid but continue with battery and/or solar to load (does this now) [while continuing to monitor grid]
Under the right conditions for the above, generate a genset start/stop signal and connect/disconnect the appropriate sources and of course notify someone [snmp, e-mail, SMS or a combination]
I have 4 CT's on my PW-2; 1 is grid, 4 is solar and was told that 2 and 3 are for use with the other 2 phases of a 3 phase installation. I do not have schematic diagrams of the internals of the EG or the PW-2 but had hoped these unused inputs were like the description above.
Cheers,
Harry E.
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@he1957 Sorry, I don't have info on the API but it seems that some people either have official info or are hacking it. Googling "Powerwall API" turns up this page Powerwall 2 API ? | Tesla
I don't think that you need any additional connections to the Powerwall to accomplish the features that you are talking about. As you point out the Powerwall already automatically handles all the conditions except generator integration. A generator with an automatic transfer switch also provides fully automatic backup power. So we just have to make these two systems play nicely with each other. My thinking is that no modification to the Powerwall operation is necessary. All I am proposing is that we let generator take the place of the grid but only when the Powewall is about to die. So the generator transfer switch has to be between the Powerwall Backup Gateway and the grid. When the generator turns on, the Powerwall will just think that the grid came back up. However, we probably need to disconnect the solar panel grid interactive inverter whenever the generator is connected because we can imagine bad things happening if the grid interactive inverter tries to push power to the generator.
Normally, the generator would come on as soon as the grid goes down. We don't want that because solar and the Powerwall are our preferred sources of power. The generator and its transfer switch have their own controller which senses the grid going down and powers up the generator and disconnects the grid and connects the generator. Generator controllers typically also exercise the generators once a week without disconnecting the grid. Therefore, it would be best leave the generator controller functioning as undisturbed as possible. We do have to modify the generator operation to suppress the generator when power is available from the Powerwall. @shs1 who started this thread said that his Kohler generator has an input that does just that.
So my idea is to build a third controller which I will call the "custom controller". The custom controller reads the state of charge (SoC) from the Powerwall. When the SoC gets to 10% the custom controller energizes two relays (contactors). One relay disconnects the solar panel grid interactive inverter and the other relay allows the generator controller to fire up the generator. (The generator controller already knows that there is no power from the grid.) Once the generator is powered up and switched in the Powerwall will thinks that the grid is back up and start taking power from its grid connection. The custom controller could let the generator run until the Powerwall was up to 90% which would give the generator the longest possible duty cycle. I would set my custom controller to turn the generator off when the Powerwall reached 50% because there is a chance that the sun has come out and the solar panels will be able to take over supplying power and charging the Powerwall and we would rather get our power from the solar panels than the generator if we can. The problem is that we disconnected the solar panels to run the generator so the only way to give the solar a chance to take over is to turn the generator off and reconnect the solar.
The bottom line is that the generator kicks in only when the batteries are about to die. When the batteries get back to 50% we let the batteries take over supplying power again. This setup lets the Powerwall and the generator cycle back and forth for as long as necessary until either the grid or solar can supply power and keep the Powerwall charged. It also utilizes the generator as efficiently as possible because the generator is charging the Powerwall which means that it doesn't have to run continuously.
There are three small downsides:
Downside 1: We don't get any benefit from solar while the custom controller is calling for the generator. This probably isn't too much of a loss because if the sun was shining the Powerwall probably would not have dropped to 10% in the first place. With the ample power that the generator can supply the Powerwall will charge from 10% to 50% in about an hour so that will be the on time of the generator. That will also be the time that we will go without the benefit of solar. And that will also be the time that we wait before checking to see if the solar has kicked in.
If the grid comes back on line while the custom controller is calling for the generator, the generator controller will shut down the generator and connect the grid regardless of what the custom controller input to the generator controller says to do. If we did nothing else, the custom controller would keep the solar disconnected until the battery gets up to 50%. That wouldn't be so bad. However, it would be easy to add a circuit to our custom controller to detect if the grid comes back on line and shut down the custom controller's "generator cycle". That would patch the solar back in without having to wait for the battery to reach 50%.
Downside 2: The generator will not be available to supplement solar and the Powerwall with peak power the way that the grid normally does. However the only way to do that would be to run the generator continuously while the grid was down which we don't want to do anyway. What we do want is for the generator to run as little as possible but when it is running we want it to be delivering close to its full rated output because that is where it is most efficient. We should size the generator at 50% to 100% higher in power than the Powerwall's maximum charge rate. The generator is primarily working as a battery charger but it also has to power the building at the same time that it is charging the battery.
Downside 3: We have to think in terms of living within a power budget whenever the grid is down. That budget is basically whatever the Powerwall can provide assuming no grid, no solar and no generator. If any of those other power source happen to be available, then we can exceed the budget but there is no guarantee that any of them will be available. It would be possible to add a manual override switch that forced the generator on. You would throw that switch when you knew that you needed more power than the Powerwall plus solar could provide. I would make that switch a three way switch with a position that prevented the generator from ever turning on. That would be be a good thing to have if you needed to ration fuel for the generator. (The generator controller will ignore the custom controller as long as the grid is up so the manual override switch will only take effect when the grid is down.)
I don't think that you need any additional connections to the Powerwall to accomplish the features that you are talking about. As you point out the Powerwall already automatically handles all the conditions except generator integration. A generator with an automatic transfer switch also provides fully automatic backup power. So we just have to make these two systems play nicely with each other. My thinking is that no modification to the Powerwall operation is necessary. All I am proposing is that we let generator take the place of the grid but only when the Powewall is about to die. So the generator transfer switch has to be between the Powerwall Backup Gateway and the grid. When the generator turns on, the Powerwall will just think that the grid came back up. However, we probably need to disconnect the solar panel grid interactive inverter whenever the generator is connected because we can imagine bad things happening if the grid interactive inverter tries to push power to the generator.
Normally, the generator would come on as soon as the grid goes down. We don't want that because solar and the Powerwall are our preferred sources of power. The generator and its transfer switch have their own controller which senses the grid going down and powers up the generator and disconnects the grid and connects the generator. Generator controllers typically also exercise the generators once a week without disconnecting the grid. Therefore, it would be best leave the generator controller functioning as undisturbed as possible. We do have to modify the generator operation to suppress the generator when power is available from the Powerwall. @shs1 who started this thread said that his Kohler generator has an input that does just that.
So my idea is to build a third controller which I will call the "custom controller". The custom controller reads the state of charge (SoC) from the Powerwall. When the SoC gets to 10% the custom controller energizes two relays (contactors). One relay disconnects the solar panel grid interactive inverter and the other relay allows the generator controller to fire up the generator. (The generator controller already knows that there is no power from the grid.) Once the generator is powered up and switched in the Powerwall will thinks that the grid is back up and start taking power from its grid connection. The custom controller could let the generator run until the Powerwall was up to 90% which would give the generator the longest possible duty cycle. I would set my custom controller to turn the generator off when the Powerwall reached 50% because there is a chance that the sun has come out and the solar panels will be able to take over supplying power and charging the Powerwall and we would rather get our power from the solar panels than the generator if we can. The problem is that we disconnected the solar panels to run the generator so the only way to give the solar a chance to take over is to turn the generator off and reconnect the solar.
The bottom line is that the generator kicks in only when the batteries are about to die. When the batteries get back to 50% we let the batteries take over supplying power again. This setup lets the Powerwall and the generator cycle back and forth for as long as necessary until either the grid or solar can supply power and keep the Powerwall charged. It also utilizes the generator as efficiently as possible because the generator is charging the Powerwall which means that it doesn't have to run continuously.
There are three small downsides:
Downside 1: We don't get any benefit from solar while the custom controller is calling for the generator. This probably isn't too much of a loss because if the sun was shining the Powerwall probably would not have dropped to 10% in the first place. With the ample power that the generator can supply the Powerwall will charge from 10% to 50% in about an hour so that will be the on time of the generator. That will also be the time that we will go without the benefit of solar. And that will also be the time that we wait before checking to see if the solar has kicked in.
If the grid comes back on line while the custom controller is calling for the generator, the generator controller will shut down the generator and connect the grid regardless of what the custom controller input to the generator controller says to do. If we did nothing else, the custom controller would keep the solar disconnected until the battery gets up to 50%. That wouldn't be so bad. However, it would be easy to add a circuit to our custom controller to detect if the grid comes back on line and shut down the custom controller's "generator cycle". That would patch the solar back in without having to wait for the battery to reach 50%.
Downside 2: The generator will not be available to supplement solar and the Powerwall with peak power the way that the grid normally does. However the only way to do that would be to run the generator continuously while the grid was down which we don't want to do anyway. What we do want is for the generator to run as little as possible but when it is running we want it to be delivering close to its full rated output because that is where it is most efficient. We should size the generator at 50% to 100% higher in power than the Powerwall's maximum charge rate. The generator is primarily working as a battery charger but it also has to power the building at the same time that it is charging the battery.
Downside 3: We have to think in terms of living within a power budget whenever the grid is down. That budget is basically whatever the Powerwall can provide assuming no grid, no solar and no generator. If any of those other power source happen to be available, then we can exceed the budget but there is no guarantee that any of them will be available. It would be possible to add a manual override switch that forced the generator on. You would throw that switch when you knew that you needed more power than the Powerwall plus solar could provide. I would make that switch a three way switch with a position that prevented the generator from ever turning on. That would be be a good thing to have if you needed to ration fuel for the generator. (The generator controller will ignore the custom controller as long as the grid is up so the manual override switch will only take effect when the grid is down.)
Well, you know the times when the inverters won't be generating any power - the times of the day when it's dark outside. As long as you know the time and date, you can tell if it's daytime. You can also tell if the the grid is active from the automatic transfer switch. When it comes back you can always switch the genset off, there is no downside to doing that. And then if it's daytime you can switch the inverters on too.
If you really had confidence in the rapid shutdown features, theoretically you won't need a separate switch from the genset transfer switch. You'd just tell them over whatever comms mechanism they used to shutdown until otherwise told, and that would be it. If you had internet service you could even tell from the weather forecast how high to charge the PW when on genset power - full power if it was going to be cloudy.
Of course this is all theory, and not code. Not sure about what the NEC says about this.
If you really had confidence in the rapid shutdown features, theoretically you won't need a separate switch from the genset transfer switch. You'd just tell them over whatever comms mechanism they used to shutdown until otherwise told, and that would be it. If you had internet service you could even tell from the weather forecast how high to charge the PW when on genset power - full power if it was going to be cloudy.
Of course this is all theory, and not code. Not sure about what the NEC says about this.
The two long posts above are making things overly complicated.
1. The Tesla gateway already knows how much the solar circuits are generating at any given time. The PowerWall needs to make sure that there is absolutely no back-feed into the generator. Knowing the solar output and the house load along with its own ability to charge, it knows whether it's safe to connect to the generator.
2. The residential standby generators I've seen have a separate 120V circuit that charges the 12V battery that starts the generator. If that circuit loses power, it is assumed that the grid is down and after a delay, the generator automatically starts and the automatic transfer switch engages. If you fed that circuit from the critical loads panel backed up by the PoweWall and put a relay inline controlled by the gateway logic, it could control when the generator starts.
3. There is still a fundamental question about the power quality of most standby generators. Is it good enough for the PowerWall to sync to it and for solar inverters to continue working?
1. The Tesla gateway already knows how much the solar circuits are generating at any given time. The PowerWall needs to make sure that there is absolutely no back-feed into the generator. Knowing the solar output and the house load along with its own ability to charge, it knows whether it's safe to connect to the generator.
2. The residential standby generators I've seen have a separate 120V circuit that charges the 12V battery that starts the generator. If that circuit loses power, it is assumed that the grid is down and after a delay, the generator automatically starts and the automatic transfer switch engages. If you fed that circuit from the critical loads panel backed up by the PoweWall and put a relay inline controlled by the gateway logic, it could control when the generator starts.
3. There is still a fundamental question about the power quality of most standby generators. Is it good enough for the PowerWall to sync to it and for solar inverters to continue working?
When I spoke with my Tesla Certified Powerwall Installer yesterday, he seemed pretty blown away. He had just got off the phone with Tesla and they informed him that the Tesla Certified Powerwall Installer program was being suspended at the end of the month and after that he would no longer be able to sell me a second Powerwall or represent Tesla. I was blown away too as he is a friend and he and his wife own a small business that has recently invested in the Tesla universe by having he and his people take the training course and hiring a guy to do the SGIP paperwork, etc.. Is he now just supposed to write off all the effort, time and money that he spent in training people, finding Powerwall customers to whom he can no longer sell, etc.?
And where does that leave me and my unfinished install? I had a Tuff Shed installed on September 1st and my Powerwall 2 was placed therein shortly after, but the installation has been held up largely because we have been trying to figure out a Tesla approved Powerwall/generator interface that will allow the same reliable automatic operation that we currently have without the Powerwall. We were going to get things up and running with the single Powerwall 2 that I already paid for and then add a second if needed. Now I have to “buy” a 2nd one by the end of the month if I want it, but likely won’t get it till at least March.
When I spoke to him about the whole mess today, he added that he had just received an email from Tesla that suggested some new development in the generator interface area. I guess that might be good news, but this whole thing makes me wonder what is going on at Tesla. Time to sell the stock I have owned for more than 5 years from the time I reserved our Model S? Do I really want to exercise my Model 3 reservations? Very disturbing and hard to understand.
Anyone else hearing anything about this?
And where does that leave me and my unfinished install? I had a Tuff Shed installed on September 1st and my Powerwall 2 was placed therein shortly after, but the installation has been held up largely because we have been trying to figure out a Tesla approved Powerwall/generator interface that will allow the same reliable automatic operation that we currently have without the Powerwall. We were going to get things up and running with the single Powerwall 2 that I already paid for and then add a second if needed. Now I have to “buy” a 2nd one by the end of the month if I want it, but likely won’t get it till at least March.
When I spoke to him about the whole mess today, he added that he had just received an email from Tesla that suggested some new development in the generator interface area. I guess that might be good news, but this whole thing makes me wonder what is going on at Tesla. Time to sell the stock I have owned for more than 5 years from the time I reserved our Model S? Do I really want to exercise my Model 3 reservations? Very disturbing and hard to understand.
Anyone else hearing anything about this?
zanary
Active Member
Selling your stock, and cancelling your Model 3 reservation seems pretty extreme. Here is my thoughts
(1) Tesla has been very keen on doing everything themselves... insourcing. So while they had authorized installers for Powerwall and Solar Panels, my guess is that they are going to insource everything eventually, city by city and state by state as they setup local presence. They've started to revamp some of their Tesla stores in and around the SF Bay Area to now showcase, sell all of their products including all of they residential energy offerings (ie, Powerwall, Panels, and Roof Tiles, etc...)
(2) Tesla is still pushing out the latest PowerwallIOS 1.10.2 (I'm still on 1.9.2 right now). I called about upgrading mine, and they informed me that their install base is so large, that they now now following the same cadence as the vehicles, in that they can't take one off push requests over the phone (I've done it twice already in the past few months). All of their Powerwall installations are divided amongst three large groups, and each group will get their firmwares updates over the course of a few weeks... Powerwall OS 1.10.2 contains APNS support and a bunch of other fixes. Time of Use Load Shifting is still in development and is not likely to happen by Dec 31st as they originally had planned. There is no ETA for that feature to become available to non PV owners.
There may be other reasons, but this is what I can extrapolate based on their past behavior and their need or want to do everything themselves (ie, insourcing)...
It could be that Tesla didn't want to deal with the scalping that some Tesla Certified Powerwall Installers were doing, and they decided that the best/easiest way to deal with that was to just kill the program all together and do everything themselves. Or maybe they were having issues with the average quality of work and it was creating support problems. (We will likely never know the actual reason.)
As far as your contractor, that is something small businesses have to think about before investing in something like this. Some won't do it without getting a guarantee about how long the program will exist.
A similar thing happened back in the "olden" days with Apple. Apple licensed third party companies to make PC that could run MacOS and the program was so successful that it hurt Apple hardware sales so they killed the program. All the companies that invested in getting setup and approved to create MacOS compatible PCs were essentially put out of business overnight.
I certainly remember those days with Apple as I started using a Mac in 84 with the 128K and attended Mac World since I worked in Silicon Valley. These things happen; I would have hoped for better things from Tesla. Perhaps you are right that scaling was the cause.
I pre-wired and pre-plumbed my house for a natural gas generator during construction, but never got the permit or hardware for the actual generator. I will be doing PowerWalls instead. Have you thoroughly thought through the use case for the generator and PowerWalls? Will you have solar?
I doubt you can find anyone at Tesla through normal channels that knows the real story about how they will integrate with generators.
This is a good question. Yes, we'll have solar, and plenty of it - that's why I am thinking about powerwalls instead of a generator alone. I don't think powerwalls alone are reliable enough given variations in weather to be counted on to provide power as a alternative to generator service in an extended outage. The earthquakes in recent days remind me that we could easily end up with several days if not weeks of power outage from the grid. And if those days happened to occur during winter and lots of clouds, solar alone may not be able to keep up. Of if there are a spate of storms that take out trees that take out transmission lines, PG&E may not be able to fix them all quickly.
So my view is that I need a generator. Note that I am thinking about a diesel generator, not a gas one, as again in a large earthquake I suspect the gas will fail at some point too. But once the grid power fails, without a powerwall the solar is useless. With powerwalls, the generator could be used only when the solar isn't adequate to keep things going by itself. That means whatever amount of fuel is available would last a much much longer time, if the genset only ran 3 hours a day instead of 24. So this seems like an ideal combination.
However, Tesla doesn't seem to be prioritizing generator integration, and in an extended power outage, the Internet service will also likely fail, so if the only way I can control a powerwall is through a mobile app that has to talk through the internet to the cloud and then from the cloud to the powerall, that seems pretty darn fragile as well. And the powerwall doesn't seem to be able to be changed from the generator either, which is not that big a deal, but makes the control of the system even more complicated.
So all this is why I am certain about having a generator, but not certain about adding a powerwall. Am I missing something major here? Would love to be corrected if I have this wrong.
Thanks,
mike
I would recommend spending money on the PowerWalls instead of a generator unless you have critical consumption like medical support equipment that cannot be shut down. During an extended outage like one after a major earthquake, I can go around the house and shut down luxury items like my RAID media server that normally consume electricity 24/7, so that I can stay within the limited solar generation available during the winter. If the gas goes out for several days in the winter I actually have a more severe problem because I won't have any heat. I am getting two PowerWalls so that I can ride out longer outages with my small 4.3kW solar array.
As long as you keep your LAN and WiFi powered, you should be able to connect directly to the Gateway to see the battery level and energy flows even if the internet is down.
IMHO, Tesla will have to make a significant PowerWall hardware revision to support most generators. The most obvious solution would be to add an optional AC input that is just a battery charger. The frequency and voltage on that input would be independent from the loads powered by the PowerWall inverter and solar. This is desirable because most generators have terrible waveform and frequency variations. If you're just rectifying it in a battery charger, the waveform really doesn't matter.
As long as you keep your LAN and WiFi powered, you should be able to connect directly to the Gateway to see the battery level and energy flows even if the internet is down.
IMHO, Tesla will have to make a significant PowerWall hardware revision to support most generators. The most obvious solution would be to add an optional AC input that is just a battery charger. The frequency and voltage on that input would be independent from the loads powered by the PowerWall inverter and solar. This is desirable because most generators have terrible waveform and frequency variations. If you're just rectifying it in a battery charger, the waveform really doesn't matter.
You have a fair point in being able to turn down demand. My worry is my wife being able to do that if I am away on a work trip, etc... Heating is not so much a problem because the house is new and will be very well insulated and tight, plus we have Mitsubishi heatpump system in it that can heat with electric super efficiently. Hot water would be an issue, but you can't have everything I suppose.
I know you can talk to the web interface on the gateway locally, but I didn't think you could control it, like moving from TOU mode to a self-use optimized mode. Can you actually change that via a local interface? The generator control on the ATS is quite easily controlled locally - no cloud connectivity required.
I don't think tesla is likely to make a big change, which results in all this complexity from a generator interface POV. It can work, and isn't really that hard, but tesla doesn't control all the pieces, and they tend to not like working with other companies, so it's too bad.
But if we could make that work, I would love to be able to leverage Solar in an extended outage.
I know you can talk to the web interface on the gateway locally, but I didn't think you could control it, like moving from TOU mode to a self-use optimized mode. Can you actually change that via a local interface? The generator control on the ATS is quite easily controlled locally - no cloud connectivity required.
I don't think tesla is likely to make a big change, which results in all this complexity from a generator interface POV. It can work, and isn't really that hard, but tesla doesn't control all the pieces, and they tend to not like working with other companies, so it's too bad.
But if we could make that work, I would love to be able to leverage Solar in an extended outage.
We live in the Sierra and right after we finished building our house 8 years ago, we had a snow storm that took out power. And because the outage was very widespread, it took awhile for PG&E to get up our neighborhood and we were without power for well more than a week. During that week there was not much sun. We were glad we had our generator to heat the house, cook dinner, etc. We have also had years where we have no power failures that lasted more than a few hours. Because of the uncertainly of how much the generator might be used in any given year, we chose propane as it can be stored without deterioration. So if it is not used for a few years, no problem.
Since we already had the generator, I wanted to see it incorporated in our power backup strategy. If starting from scratch, it might be different, but probably not. And not we have 2 Tesla to charge.
Since we already had the generator, I wanted to see it incorporated in our power backup strategy. If starting from scratch, it might be different, but probably not. And not we have 2 Tesla to charge.
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